Refrigerating apparatus



May 27,1941. A. A. KUCHER 3,

v REFRIGERATING APPARATUS Filed March 25, 1940 IN VENT OR Amman 14. kllcflil,

1m- ATTORNEYS.

Patented May 27, 1941 REFRIGERATING APPARATUS Andrew A. Kucher, Dayton, Ohio, assignor to General Motors Corporation, Dayton, Ohio, a

corporation of Delaware Application March 25, 1940, Serial No. 325,737

6 Claims.

This invention relates to two-temperature refri'gerating systems and particularly to a multi stage compressor therefor.

It is an object of my invention to provide an improved compressor unit for a refrigerating system commonly referred to as a two-temperature system wherein a. plurality of evaporators are maintained at different temperatures relative to one another and wherein a multi-stage compressor is employed to create different refrigerant evaporating pressures in the evaporators and to circulate refrigerant throughout the closed system to thereby take care of the refrigeration demands placed upon the various evaporators.

Another object of my invention is to provide a hermetically sealed motor and multi-stage rotary compressorunit for a two-temperature 'refrigerating system wherein the compressor comprises two refrigerant compression chambers each having an inlet and an outlet with the outlet of one chamber communicating with the inlet of the other chamber and having this point of ing with the other compression chamber thereof whereby refrigerant entering the sealed unit by way of the one inlet is compressed in stages in both chambers and refrigerant entering the unit by way of the other inlet is compressed only in the other chamber of the multi-stage compres- SOI.

It is a further and more specific object of my invention to provide a sealed motor and multistage rotary compressor unit of the type described in the preceding objects, wherein the casing providing the sealed enclosure forms a part of the high pressure portion of a two-temperature refrigerating system and wherein the high pressure within the casing is utilized for causing oil therein to seal operating parts of the compressor portions of the unit and for causing the oil to circulate to operating parts or bearings of the unit. o

Flu'ther objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing, wherein a preferred form of the present invention is clearly shown.

I have shown in the drawing a transverse vertical sectional view through a motor-compressor unit having features of my invention embodied therein and illustrating a refrigerating system diagrammatically connected therewith. V

Referring to the drawing, there is shown a sealed motor-compressor unit, generally represented by the reference character l0, forming a part of a closed refrigerating system. Unit [3 comprises a cast metal spider-like main frame ll having a central upright portion l2 provided with a vertical bore l4 forming a bearing for a shaft l5. Frame II is provided with an upright wall 16 concentricwith the shaft bore I4 and with a horizontally disposed shoulder ll. Frame II is also provided with a lower plane finished horizontal surface l8 which serves a purpose to be hereinafter described. The motor of unit l0 includes a motor stator I!) supported by the wall l6 of frame II. The windings of the motor I stator l9 may be connected by a suitable lead or leads 2| and a terminal or terminals 22, sealed to the wall of a dome 23 which fits over frame II, to a source of electric current exteriorly of the sealed unit. A metal element 26 is rigidly secured to the upper end of shaft I5 in any suitable manner such as by being tightly pressed thereon and amotor rotor 21, disposed within the stator I3. is rigidly secured to element 26 by being pressed thereon. Element 26 is provided with a central cylindrical bore 28 which loosely fits over and surrounds the upper wall portion 29 of shaft bearing l2. A thrust washer 3| is disposed between element 26 and the upper end of wall portion 23, and this washer has a groove or grooves 32 provided in its lower face.

A lower housing 36 provided with an intumed top edge 31 receives shoulder H on dome 23 and houses the compressor portion of umt Ill and.

forms a sump or reservoir for a body of oil. Dome 23 has an outwardly extending lower portion 33 which fits over the top of housing 36 and is welded thereto to rigidly secure frame ll, dome 23 and housing 36 together to provide a sealed enclosure. The compressor of unit I3 is of these-called multi-stage type and specifically includes two fluid compression chambers each having a rotor and a plurality of blades therein and each being of substantially the same construction and design as the rotary compressorv clearly shown and fully described in the copending application of Francis I. Rataiczak, Serial No. 248,888, filed December 31, 1938. In the present disclosure the compressing means or compressors are directly connected with the motor shaft l5 and one compressionchamber ls superimposed upon the other. A block member 4| having an opening-i2 therein, which constitutes a rotor or compression chamber, surrounds the shaft l5 and is held in sealing engagement with the finished plane surface l8 on the bottom of frame A plate 43 abuts the underside of block 4| to provide a closure for the rotor chamber opening 42 therein. Motor shaft I5 extends through the rotor chamber 42 -of block 4| and through plate 43. A rotor, indicated by the dotted line 45, is located within rotor chamber 42 and is keyed to shaft l5 by a plurality of pins 46 arranged in pairs with one pair thereof disposed at right angles to the other pair andpassing through suitable openings in the shaft. Pins 46 abut blades 41 mounted in suitable slots 48 provided therefor in rotor 45. Each blade 41 has a sealing or rubbing block 5| associated therewith and engaging wall 42 of the rotor chamber. It is preferable to provide the rotor 45 with four of the blades 41 as in the structure disclosed in the copending application above referred to. The dimension over the pins 46 and their associated blades and sealing or rubbing blocks is predetermined or fixed. The rotor 45 is concentric with shaft I5 and the wall of rotor chamber 42 is eccentric relative to shaft l5 and rotor 45. Thus the horizontal cross-section of compression or rotor chamber 42 may have an irregular circumference or a circumference of a contour corresponding to a limacon curve in order to insure engagement of the blocks 5| of blades 41 with the wall of chamber 42' means during rotation of and in accordance with the position of rotor 45 relative to inlet and outlet ports.

Below plate 43 is a second refrigerant oom- .pressing means which includes elements corre-- sponding to the elements of the upper or first compressing means. The second or lower compressing means comprises a block member 4|a having an opening 42a therein, which constitutes a rotor or compression chamber, and surrounds the lower end of shaft l5. A bottom plate 46a is held in sealing engagement with block member 4la by a able openings provided in plate 43a, block member 4|a, plate 43, block member 4| and are threaded into threaded openings provided in main frame H to hold parts ofthe refrigerant compressing means together. A rotor, indicated by the dotted line 45a, is located within rotor chamber 42a and is keyed to shaft l5 by a plurality of pins 46a arranged in pairs with one pair thereof disposed at right angles to another pair and passing through suitable openings provided in the shaft. Pins 46a abut blades 41a mounted in slots 46; blades 41a and blocks 5|a will be reciprocat present disclosure, the elements of the second or lower rotary compressing means are similar to the elements of the first or upper rotary compressing means of the multi-stage compressor. In order to increase the capacity of the second compressing means of the multistage compressor its elements or parts are made largerthan the elements or parts of the first compressing means. For example, the capacity of volumetric displacement of the second or lower rotary compressing means may be increased by making its rotor or compression chamber 42a and rotor 45a of greater diameter than these corresponding parts of the upper rotary compressing means. The capacity or the volumetric displacement of the lower compressing means may also be increased by making its rotor chamber 42a, rotor 45a, blades 41a and blocks 5|a wider than their corresponding parts of the upper compressing means. The greater capacity of the lower rotary compressing means over the upper rotary compressing means is for a purpose that will become obvious from the following description.

An inlet connection, formed by adetachable conduit or pipe fitting, generally represented by the numeral 56 and described in detail in the ooplurality of bolts 56. Bolts 56 pass through suit- 46a provided therefor in the rotor 45a. Each blade 41 has a sealing block 5|a associated with I its outer end and the blocks 5|a engage wall 42a of the rotor chamber. The rotor 450 like rotor.

45 is preferably provided with four of the blades 41a and blocks 5Ia The dimension over pins 46a and their associated blades and sealing blocks is, like in the first or upper compressing means,

pending application above referred to extends throughand is' sealed to the wall of lower housing 36 and communicates with an inlet port 56 provided in block member 4| of the upper compressing means. A discharge port 6| provided in block member 4| is normally covered by a suitable check valve 62. The lower compressing means is also provided with a discharge port 6|a provided in its block member Ho and is normally covered by a suitable check valve 620.. An inlet port 59a provided in block member 4|a of the lower compressing means communicates with an opening 64 provided in the plate 43 disposed between the two rotary compressing means of the multi-stage compressor. The wall of the discharge chamber 65 of the upper compressing means, which chamber is closed by a plate 66, has ,a hole 61 therein registering with the hole 64 in plate 43 and providing a conduit communication between the discharge chamber 65 of the upper compressing means and the inlet passage or port 59a of the lower compressing means. Intermediate plate 46 is provided with an enlarged portion 1| projecting outwardly from the side walls of block members 4| and 4|a and has a passage 12 therein providing communication between the conduit or passageways 61, 64 and 56a with an inlet pipe connection generally represented by the numeral 13 which is sealed to and extends through the wall of lower housing 36 of the unit. The inlet conduit or pipe connection 13 may be of a construction similar to the construction of connection 58 and, as before stated, both of these connections may be of the type fullydescribed and illustrated in the copending application above referred to. The connections 58 and 16 are, of course, sealed tohousing 66 and to their point of attachment with the compressing means in order to convey refrigerant in a closed path to the compressing means through the interior of the sealed casing. A plate 16 closing the discharge chamber 11 of the lower compressing means is provided with an outlet pipe connection 16--to which apipe 16 is connected. Pipe 19 extends upwardly from the multi-stage compressor and its end 6| terminates at a point above the bottom wall or web portion d within the slots 46a. of rotor 45a. In the of frame II and refrigerant isdischarged through this pipe into the sealed enclosure formed by housing 38 and dome 23. Since the interior of the sealed unit is under high pressure or is subjected to compressor discharge pressure, I prefer to maintain a body of oil in theunit, the level of which is indicated at 82. This body of oil 82 serves a double purpose in that it seals the two compressing means which are submerged in the oil and is utilized for lubricating operating parts of the multi-stage compressor and the motor shaft hearing. A screen 84 secured to the bottom plate 43a by screws 85 filters oil adapted to be circulated to operating parts of the unit. The lower end portion of shaft I is provided centrally thereof with a vertical bore 85 extending from its lower endto a point above the plane horizontal surface I8 of frame II where it communicates with a horizontal bore 81 for a purpose to be hereinafter described. A plurality of horizontal bores 88 provided in shaft I5 communicate with the bore 86 therein and with the slots 48 and 48a of the rotors 45 and 45a. A groove 88 provided around the upper part of shaft I5 has its lower end communicating with the bore 81 and has its upper end communicating with the groove or grooves 32 provided in washer'3l. The bores and grooves just described formoil passages for lubricating the various parts of the multi-stag'e compressor and the motor shaft bearing and the oil will be circulated therethrough by the high pressure of compressed refrigerant above the body of oil and by the centrifugal action of the parts during operation of the unit.

The inlets and outlets of the two compressing means are arranged in such manner with respect to one another-that during operation of the unit the first or upper compressing means may discharge its compressed refrigerant into the inlet of the second or lower compressing means to provide a two-stage compression effect upon the refrigerant. The refrigerating system, of which the unit I8 may form a part, includes a condenser 8| having a pipe connection 82 with the refrigerant outlet 83 of unit I8 and located in the top wall of dome 23. Condenser 8I is connected to a receiver 84, and a pipe 85 leads from the receiver 84 to a plurality of refrigerant expansion devices or valves 85 and 81. An evaporator 88 is connected to valve 85 and a second evaporator 88 is connected to valve 81. Evaporator 88 has a gaseous or evaporated refrigerant conduit I8I leading therefrom and connected with the inlet connection 13 of unit I8. Evaporator 88 has a gaseous refrigerant conduit I82 leading therefrom and connected with the inlet connection 58 of unit I8. The valves 88 and 81 are automatic expansion valves which tend to feed liquid refrigerant into the evaporators when the pressures therein are reduced below a predetermined pressure limit at which the evaporators are adapted to perform their refrigerating effect. This action of the expansion valves in the present disclosure is modified by thermostatic bulbs, one of which bulbs I88, is placed in thermal contact with the outlet of evaporator 88 and another bulb I84 is placed in thermal contact with the outlet of evaporator 88. The operation of the motor of unit I8 may be controlled by any suitable control device (not shown) such, for example, as a thermostatically actuated snap switch wherein the thermostat connected to. the switch functions in response to the temperature of either of the evaporators 88 or 88 or to the temperature of the medium cooled thereby. In the present" disbeing cooled by evaporator 88 at a relatively low refrigerant pressure or temperature. A feature of the present invention is the provision of a multi-stage sealed motor and compressor unit which forms part of the high pressure side of a refrigerating system or which is subjected to compressor discharge pressure and which includes means for introducing evaporated refrigerant from one evaporator into one of the compressing means to insure compression thereof in stages in both compressing means and meansfor introducing evaporated refrigerant from another evaporator into the other compressing means to insure compression thereof in a single compressor.

In the operation of unit I8, motor rotor 21 is rotated by energizing motor stator I8 and due to the rigid connection of motor rotor 21 with shaft I5 through element 26 the shaft I5 rotates to cause operation of the compressing means of the unit. Rotation of rotor 45 and its associated blades 41 and blocks 5| by shaft I5 within the eccentric chamber 42 causes evaporated or gaseous refrigerant to be withdrawn from evaporator 88 through pipe I82. Connection 58 communicating with pipe I82 directs the gaseous refrigerant intothe compression chamber 42 in the space between the rotor 45 and the chamber wall intermediate the blades 41. The rotation of rotor 45, blades 41 and blocks 5| within the eccentric chamber 42 causes refrigerant to be compressed in the chamber and discharged therefrom through port GI and into chamber 85. Refrigerant from the compression chamber 42 flows from discharge chamber 55 into hole 81 and through hole 64 in plate 43 to the inlet port'58a of the lower compression chamber 42a. As before stated, the compressing means are so arranged with respect to one another that the rotor of the lower compression chamber is located in a position relative to the'discharge position of the rotor of the upper compression chamber as to draw into the compression chamber 42a refrigerant discharged from the upper chamber 42 to provide successive stages of compression for therefrigerant withdrawn from evaporator 88. Hole 12 directs gaseous refrigerant flowing from the evaporator 88 by way of pipe "I and connection 13 into the conduit or passage 84. Here the vaporous refrigerant from evaporator 88 is commingled with the compressed or partially compressed vapor from evaporator 88, discharged from the upper chamber 42,'and enters the compression chamber 420. therewith by way of inlet port 58a. As before stated, the lower or second compression chamber 42a may be and is preferably of increased volumetric displacement over the upperor first chamber 42 to take care of the additional refrigerant vapor from evaporator 88.

ciated elements of the first or upper compressing means causes a further stage of compression of refrigerant from evaporator 88 and a single or complete compression of refrigerant from evaporator 99. Refrigerant discharged from the port 6 la of the second compression chamber 42a flows from discharge chamber Tl through connection 18 upwardly through the body of oil 82 by way of pipe 19 and is directed by the end 8| of pipe 19 above the-body of oil and into the upper or motor portion of the sealed unit. The motor end of unit l may, if desired, be cooled by any conventional or suitable cooling means such, for example, as by placing fins on dome 23 or by wrapping a water cooling coil around the dome. The completely compressed high pressure refrigerant is conveyed out of the sealed unit In through connection 8'3 and is directed through pipe 92 to the condenser 9| where it is cooled and liquefied and stored in receiver 94. Liquid refrigerant is distributed to the evaporators 98 and 99 by way of pipe 95 and under control of the automatic expansion valves 98 and 91 in response to the temperature of the outlet of the evaporators with which the bulbs I03 and I04 are associated.

During operation of the motor and multi-stage compressor of unit [0, the high pressure or compressed refrigerant within the sealed unit in the space therein above the body of oil acts upon the oil level and causes oil to flow upwardly through the bore 86 in the lower end of shaft I and through the holes 88 to lubricate operating parts of the compressing means. Some of this oil flows upwardly of bore 88 through the hole 81 in shaft I5 to the spiral oil groove 88 provided in the surface of'the shaft. Oil in the groove 89 lubricates the hearing I! of shaft l5 and flows up- 2,24a,4ee

described with two refrigerant fluid inlet connections which makes possible the use of a hermetically sealed motor and multi-stage rotary compressor for certain forms of refrigerating systems, which systems would otherwise be complicated and of such cost as to render them impractical. A

While the form of embodiment of the invention as herein disclosedconstitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What isclaimed is as follows:

1. A sealed unit comprising in combination, a casing having a motor and a compressor disposed therein, said casing being under compressor discharge pressure, said motor having a shaft extending therefrom, said compressor including a plurality of fluid compressing means driven by wardly around the shaft'to the groove or grooves 32 provided in washer 3|. This oil flows outwardly of groove or grooves 32 and downwardly around the upper wall 29 of frame II to return to the body thereof in the sealed enclosure. Either or both of the compression chambers of unit l0 may, if desired, be provided with relief valves positioned close to the discharge ports of the compressors to prevent oil which may flnd its way into the rotor or compression chambers 42 and 42a from creating excessive or abnormal pressure therein. The relief valve or valves may be of the construction and arrangement clearly shown and fully described in the copending application hereinbefore referred to. l

From the foregoing it will be apparent that I have provided a two-stage hermetically sealed motor-compressor unit wherein the interior of the sealed unit is under compression discharge pressure or, in other words, forms a part of the high pressure side of a refrigerating system of the type including a plurality of evaporators maintained at different temperatures relative to one another. In my improved motor and multistage compressor unit the oil therein is under high pressure, thus permitting two rotary compressing means to be disposed in a sealed unit whereby the oil seals operating parts of both and also serves to efliciently lubricate parts of the compressing means and the shaft bearing. The features of my invention make possible the construction'of a multi-sta e compressor directly connected with and operated simultaneously from a single motor wherein the motor and compressor are all enclosed in a sealed unit to thus eliminate exposed operating elements. Furthermore, and in accordance with the objects of the invention, I have provided a unit of the type said motor shaft, each of said plurality of fluid compressing means having an inlet and an outlet, a pipe sealed to and passing through a wall of said casing and communicating with one of said compressing means for conveying fluid thereto from exteriorly of the casing, a closed conduit communicating with the outlet of said one compressing means and with the inlet of another of saidcompressing means for conveying nuid compressed by said one compressing means to said another compressing means whereby fluid entering said compressor through said pipe is compressed in stages by both compressing means and thereafter discharged into said sealed unit, and a' second pipe sealed'to and passing through a wall of said casing and communicating with said closed conduit for conveying fluid directly to said another compressing means from exteriorly of said casing whereby fluid entering said compressor through said second pipe is compressed only by said another compressing means and thereafter discharged into said sealed unit.

2. A sealed unit comprising in combination, a casing having a motor and a compressor disposed therein, said casing being under compressor discharge pressure, said motor having a shaft extending therefrom, said compressor including a plurality of fluid compressing means driven by said motor shaft, one of said compressing means being of greater volumetric displacement than fluid compressed by said another compressing means to said one compressing means whereby the fluid entering said compressor through said pipe is compressed in stages by both compressing means and thereafter discharged into said sealed unit, and a second pipe sealed to and passing through a wall of said casing and communicating with said closed conduitfor conveying fluid directly to said one compressing means from exteriorly of said casing whereby fluid entering said compressor through said second named pipe is compressed only by the compressing means having the greater volumetric displacement.

3. A sealed unit comprising in combination, a

casing having a motor and a multi-stage compressing means disposed therein, said casing being under compressor discharge pressure, said motor having a shaft extending therefrom said compressing means including a plurality of compression chambers each having a rotor disposed therein and driven by said motor shaft, a body of oil in said casing subjected to the discharge Dressure of said compressing means, said compression chambers each having an inlet and an outlet, a pipe sealed to and passing through a wall of said casing communicating with the inlet of one of said compression chambers for conveying fluid thereto from exteriorly of the casing, a closed conduit communicating with the outlet of said one compression chamber and with the inlet of another of said compression chambers for conveying fluid compressed in said one compression chamber to said another compression chamber whereby the fluid is compressed in stages and thereafter discharged into said sealed unit above the body of oil therein to cause the discharge pressure to act upon the body of oil and circulate the oil to operating parts of said compressing means, and a second pipe sealed to and passing through a wall of said casing and communicating with said closed conduit for conveying fluid directly to said another compression chamber from exteriorly of said casing.

4. A sealed unit comprising in combination, a casing having a main frame therein provided with a central vertical bearing, a shaft within said bearing, a motor having a connection with said shaft disposed above said main frame and supported thereby in the upper portion of said casing, a multi-stage compressing means disposed below said main frame and carried thereby in the lower portion of said casing, said casing being under compressor discharge pressure, said compressing means including means forming superposed compression chambers each having a rotor disposed therein and driven by said motor shaft, a body of oil in said casing subjected to the discharge pressure of said compressing means and surrounding said compression chamber forming means, said superposed compression chambers each having an inlet and an outlet, a pipe sealed to and passing through a wall of said casing communicating with the inlet of one of said compression chambers for conveying fluid thereto from exteriorly of the casing, a closed conduit communicating with the outlet of said one compression chamber and with the inlet of another of said compression chambers for conveying fluid compressed in said one compression chamber to said another compression chamber whereby the fluid is compressed in stages and thereafter discharged into said sealed unit above the body of oil therein to cause the discharge pressure to act upon the body of oil and circulate the oil to operating parts of the compressing means and to said shaft bearing, and a second pipe sealed to and passing through a wall of said casing and communicating with said closed conduit for conveying fluid directly to said another compression chamber from exteriorly of said casing.

5. A sealed unit comprising in combination, a

casing having a motor and a compressing means disposed therein, said casing being under compressor discharge pressure, said motor having a shaft extending therefrom, said compressing means including a plurality of compression chambers each having a rotor disposed therein and driven by said motor shaft, a body of oil in said casing subjected to the discharge pressure of said compressing means, one of said compression chambers being of greater volumetric displacement than another thereof, each of said compression chambers having an inlet and an outlet, a pipe sealed to and passing through a wall of said casing communicating with the inlet of said another compression chamber for conveying fluid thereto from exteriorly of the casing, a closed conduit communicating with the outlet of said another compression chamber and with the inlet of said one compression chamber for conveying fluid compressed in said another compression chamber to said one compression chamber, a second pipe sealed to and passing through a wall of said casing and communicating with said closed conduit whereby fluid entering said compressing means through said second named pipe is compressed only in said one compression chamber and fluid entering said compressing means through said first named pipe is compressed in said another compression chamber thence in said one compression chamber, and means for directing fluid discharged from said compressing means into said sealed unit above the body of oil therein to cause the discharge pressure to act upon the body of oil and circulate the oil to operating parts of the compressing means.

6. A sealed unit comprising in combination, a casing having a motor and a compressor disposed therein, said casing being under compressor dis charge pressure, said motor having a shaft extending therefrom, said compressor including a plurality of compressing means driven by said motor shaft, each of said fluid compressing means having an inlet and an outlet, a pipe sealed to and passing through a wall of said casing and sealed to and communicating with the inlet of one of said compressing means, said pipe conveying fluid directly to said one compressing means from exteriorly of the casing whereby the fluid is compressed thereby. a second pipe sealed to and passing through a wall of said casing and communicating with the inlet of another of said compressing means for conveying fluid thereto from exteriorly of the casing whereby fluid conveyed by said second pipe is compressed only by said another compressing means and discharged into said sealed unit, and means sealed to a wall of said 'casing and communicating with the interior thereof for conveying fluid compressed by said compressing means to the exterior of said unit.

ANDREW A. KUCHER. 

